Interaction between Multiple Current Sheets and a Shock Wave: 2D Hybrid Kinetic Simulations

2021 ◽  
Vol 922 (2) ◽  
pp. 219
Author(s):  
M. Nakanotani ◽  
G. P. Zank ◽  
L.-L. Zhao
Keyword(s):  
Shock Wave ◽  
Cosmic Ray ◽  
Flow Speed ◽  
Efficient Production ◽  
Intensity Increase ◽  
Magnetic Islands ◽  
Continuous Increase ◽  
Cosmic Ray Intensity ◽  
Current Sheets ◽  
Tearing Instability

Abstract Particle acceleration behind a shock wave due to interactions between magnetic islands in the heliosphere has attracted attention in recent years. The downstream acceleration may yield a continuous increase of particle flux downstream of the shock wave. Although it is not obvious how the downstream magnetic islands are produced, it has been suggested that current sheets are involved in the generation of magnetic islands due to their interaction with a shock wave. We perform 2D hybrid kinetic simulations to investigate the interaction between multiple current sheets and a shock wave. In the simulation, current sheets are compressed by the shock wave and a tearing instability develops at the compressed current sheets downstream of the shock. As the result of this instability, the electromagnetic fields become turbulent and magnetic islands form well downstream of the shock wave. We find a “post-cursor” region in which the downstream flow speed normal to the shock wave in the downstream rest frame is decelerated to ∼ 1V A immediately behind the shock wave, where V A is the upstream Alfvén speed. The flow speed then gradually decelerates to 0 accompanied by the development of the tearing instability. We also observe an efficient production of energetic particles above 100 E 0 during the development of the instability some distance downstream of the shock wave, where E 0 = m p V A 2 and m p is the proton mass. This feature corresponds to Voyager observations showing that the anomalous cosmic-ray intensity increase begins some distance downstream of the heliospheric termination shock.

Cosmic ray intensity increase on May 4, 1960

1960 ◽  
Vol 17 (1) ◽  
pp. 119-121 ◽  
Author(s):  
O. R. Santochi ◽  
J. R. Manzano ◽  
J. G. Roederer
Keyword(s):  
Cosmic Ray ◽  
Intensity Increase ◽  
Cosmic Ray Intensity

scholarly journals Precursory signals of Forbush decreases with and without shock wave

2021 ◽  
pp. 57-63
Author(s):  
Dimitra Lingri ◽  
Helen Mavromichalaki ◽  
Anatoly V. Belov ◽  
Eugenia A. Eroshenko
Keyword(s):  
Magnetic Field ◽  
Shock Wave ◽  
Interplanetary Magnetic Field ◽  
Selection Criteria ◽  
Forbush Decrease ◽  
Cosmic Ray ◽  
Abrupt Increase ◽  
Cosmic Ray Intensity ◽  
Similarities And Differences ◽  
Solar Disturbances

Many previous studies have shown that before the beginning of a Forbush Decrease (FD) of the cosmic ray intensity, a precursor signal can be observed. All these surveys were focused on FDs that are associated with a sudden storm com- mencement (SSC). In this work we demonstrate that precursors could also be observed in events without a SSC that is determined by an abrupt increase of the interplanetary magnetic field. The type of precursory signals and their diversity among the events are the main purpose of this study. We try to figure out similarities and differences on the signals and the associated events from both categories in the last fifty years, from 1969 to 2019, using the same selection criteria of the under investigation FDs. Simultaneously the orientation of the upcoming solar disturbances in comparison to the way they configure the increase of the interplanetary magnetic field and create these signals are discussed.

scholarly journals Sudden Increases in Cosmic Ray Intensity

1969 ◽  
Vol 22 (1) ◽  
pp. 127
Author(s):  
R Anda ◽  
B Aparicio ◽  
LV Sud ◽  
M Zubieta
Keyword(s):  
Cosmic Rays ◽  
Solar Flare ◽  
Cosmic Radiation ◽  
Cosmic Ray ◽  
Continuous Recording ◽  
Intensity Increase ◽  
The Sun ◽  
Cosmic Ray Intensity

At different times during a period of continuous recording of cosmic rays large increases in the intensity of cosmic radiation have been observed. Most of these are associated with formations on the visible side of the Sun. However, there are two exceptions: Carmichael et al. (1961) believe that the November 20,1960 increase in intensity was due to a solar flare on the reverse side of the Sun, and Sud (1968) has shown that the intensity increase of January 28,1967 also may not be connected with chromospheric eruptions on the visible side of the Sun.

38. Solar production and modulation of cosmic rays, and their propagation through interplanetary space

1958 ◽  
Vol 6 ◽  
pp. 355-376
Author(s):  
J. A. Simpson
Keyword(s):  
Magnetic Fields ◽  
Solar Flare ◽  
De Novo ◽  
Interplanetary Space ◽  
Cosmic Ray ◽  
Specific Model ◽  
Particle Energy ◽  
Intensity Increase ◽  
Cosmic Ray Intensity ◽  
Interplanetary Magnetic Fields

The principal characteristics for changes of cosmic ray intensity as a function of time and primary particle energy are reviewed for those intensity variations which are thought to be of non-terrestrial origin. These variations are either (a) temporary increases of cosmic ray intensity arising from thede novoproduction of cosmic ray particles in the vicinity of the sun in association with some solar flares, or (b) the modulation of extra-solar cosmic radiation within the interplanetary volume by a modulation mechanism related to solar activity.The study of these variations for low-energy cosmic ray particles is also a unique tool for the investigation of interplanetary magnetic fields and other properties of interplanetary space. As an example, the cosmic ray events associated with the giant solar flare of 23 February 1956 have been studied. The experimental evidence shows that interplanetary magnetic fields must exist for the storage and redistribution of the solar flare cosmic ray particles. A more specific model indicates that disordered magnetic fields lie mainly beyond the orbit of the earth and that diffusion through these irregular magnetic fields is the prominent mechanism for particle storage. In addition, this cosmic ray intensity increase was fortunately superposed in such a way upon a change of intensity arising from a modulation mechanism that it is possible to restrict the kinds of models which account for modulation of cosmic ray intensity within the interplanetary volume.

scholarly journals 35. A new model of magnetic storms and aurorae

1958 ◽  
Vol 6 ◽  
pp. 329-331
Author(s):  
S. F. Singer
Keyword(s):  
Shock Wave ◽  
High Velocity ◽  
Ring Current ◽  
Cosmic Ray ◽  
Experimental Tests ◽  
Magnetic Storms ◽  
The Body ◽  
Sudden Commencement ◽  
Main Phase ◽  
Cosmic Ray Intensity

Three topics are discussed dealing with interplanetary phenomena. They are: (i) sudden commencement of magnetic storms[1]; (ii) main phase of magnetic storms[2]; (iii) cosmic ray effects associated with solar corpuscular emission[3].To explain the sudden commencement(SC) of magnetic storms, the reverse sudden commencement (SC*), and the pre-SC disturbances, we invoke the following model: The solar eruption produces a shock-wave which arrives at the earth 22–34 hr later. High velocity particles having a smaller interaction precede the shock-wave and cause the pre-SC bay-like disturbances at high latitudes. The shock-wave itself is retarded by the body forces produced by the geomagnetic field, but speeds up as it enters the auroral zones. In pushing out lines of force it creates the polar SC* events. Charge separation in the shock-wave produces the driving force for the SC currents which flow in the atmosphere (in accordance with Vestine's analysis).The storm decrease is produced by the high velocity particles following the shock-wave (up to 9 hr later) which enter because of field perturbations into the normally inaccessible Störmer regions around the dipole. Here they are trapped and will drift producing the ring-current which gives rise to the storm decrease. Particles with small pitch angle, however, can reach the earth's atmosphere and contribute to aurora, the air-glow, and ionospheric ionization. These particles are replenished by perturbations produced by solar influences having a 27-day recurrence. Many other particles are absorbed or scattered out of the trapping regions so that their number diminishes rapidly in a day or so, as does the magnetic storm decrease.The model thus attempts to explain for the first time the cause of the reverse sudden commencement events (SC*), the atmospheric nature of SC, the delay between SC and the main phase, the formation and decay of the ring-current. A by-product is auroral particle acceleration by a shock-wave[4].New experimental tests are suggested by the model: (i) Acoustic observations with balloons to look for the shock-wave penetrating into the atmosphere in the auroral zones. (ii) Observations with rockets or satellites to establish the location of the SC and main phase currents. (iii) Measurements of the nature and energy of the auroral particles[5].It is suggested that the cosmic ray decrease occurring with magnetic storms (Forbush events), as well as the 27-day decreases of cosmic ray intensity, are modulation effects produced primarily by the deceleration of cosmic rays in interplanetary space due to the expansion of turbulent gas clouds from the sun. The detailed mechanism depends on a statistical decrease of the initially high turbulent fields and can therefore be called an ‘inverse Swann effect’ or ‘inverse Fermi effect’. The cosmic ray intensity variation during the solar cycle is accounted for as the cumulative effect of this mechanism which operates in connexion with emission of solar gas. In this way it is possible also to account for the decrease lasting six months observed by Forbush starting in February 1946. Some experimental tests are suggested to discriminate between different theories for the origin of cosmic ray time variations[3].

scholarly journals Cosmic Ray Intensity Increase on January 28, 1967

1968 ◽  
Vol 21 (5) ◽  
pp. 755 ◽  
Author(s):  
LV Sud
Keyword(s):  
Solar Cycle ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
The Other ◽  
Intensity Increase ◽  
Cosmic Ray Intensity

During the present solar cycle, which started in October 1964, the ground-based cosmic ray detectors have so far recorded two increases in the intensity of cosmic rays. The first one was observed on July 7,1966 and the other on January 28,1967. Both these events were somewhat unusual in their characteristics.

High-energy cosmic ray intensity increase of nonsolar origin and the unusual Forbush decrease of August 1972

1974 ◽  
Vol 79 (16) ◽  
pp. 2269-2280 ◽  
Author(s):  
S. P. Agrawal ◽  
A. G. Ananth ◽  
M. M. Bemalkhedkar ◽  
L. V. Kargathra ◽  
U. R. Rao ◽  
...  
Keyword(s):  
Forbush Decrease ◽  
Cosmic Ray ◽  
High Energy ◽  
Intensity Increase ◽  
Cosmic Ray Intensity
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